The Journal of Experimental Medicine

Hammon, W. McD.; Reeves, W. C.

doi: 10.1084/jem.83.3.163pmid: N/A

1. Chickens inoculated subcutaneously with 0.2 cc. of a 10 –2 to 10 –7 dilution of Western equine mouse brain virus had the virus in the blood serum between the 12th and the 48th hour in most instances. The fowls showed no signs of illness. 2. Viremia could be induced regularly in chickens by inoculating subcutaneously the least amount of virus which would produce encephalitis in the mouse when inoculated by the intracerebral route. 3. Even the minimal infecting dose for a chicken led to such multiplication of the virus that it was detectable in the serum in a 10 –4 dilution. Moreover, a minimal infecting dose appeared to result in a longer period of viremia than was produced by a larger dose. 4. Virus has not been found to persist for more than 3 days after inoculation in any organ of the chicken tested for it and usually it did not persist over 2 days. Antibodies were present in the blood within at least 15 days after inoculation. 5. It is concluded that chickens may serve as sources of infection for mosquitoes or other blood-sucking ectoparasites for short periods of time after the infecting bite of a similar invertebrate vector. There is no evidence that the chicken serves as a latent carrier of the virus. 6. No virus could be found in the blood of 2 inoculated calves, and virus has not been demonstrated regularly or with the same case in the blood of horses or of men, as it has in that of chickens. It seems unlikely therefore that large mammals serve frequently as sources for mosquito infection. 7. These experimental data on fowls and mammals correlate well with other epidemiological and laboratory findings, in particular with the feeding preference of the mosquitoes found infected in epidemic areas. Footnotes Submitted: 30 October 1945

Hammon, W. McD.; Reeves, W. C.; Izumi, E. M.

doi: 10.1084/jem.83.3.175pmid: N/A

1. Of three species of mammals tested by peripheral inoculation (guinea pig, cat, and horse) none showed viremia under conditions which suggested that any of these species would serve as a frequent source of mosquito infection. 2. Of the birds tested (chicken, duck, and dove) all developed viremia and might readily serve as natural sources of mosquito infection. Chickens were shown to be very highly susceptible to infection by minute amounts of virus inoculated subcutaneously. 3. Virus may appear in the blood of chickens within 16 hours after inoculation and it has persisted till at least the 120th hour. No fowl showed any sign of illness as a result of the infection. Footnotes Submitted: 30 October 1945

Reeves, W. C.; Hammon, W. McD.

doi: 10.1084/jem.83.3.185pmid: N/A

In the present studies ten common species of Western North American mosquitoes have been tested for their ability to act as vectors of Japanese B encephalitis virus (see summary Table XII). The strain of Japanese B encephalitis virus which was used was adapted to direct mouse brain passage, probably a disadvantage, but no freshly isolated strain was available. Of the ten species of mosquitoes tested, seven were demonstrated to be laboratory vectors. These seven species represent three genera ( Culex, Aedes , and Culiseta ). In previously reported work Japanese and Russians had only incriminated five species of two genera ( Aedes and Culex ) (1–3). Transmission was made to mice 21 times and to a chicken once. Two attempts to infect mosquitoes from an infected chicken were unsuccessfui, but no significance is attached to so few experiments. Repeated tests for virus in the eggs, or in imagines reared from eggs of infected female mosquitoes have been negative. In this we failed to confirm results claimed by Japanese investigators (5, 6). These data, in addition to the published accounts by Japanese and Russian workers of the natural epidemiology of this disease lead us to believe that this virus might well establish itself in North America, especially if introduced in those areas where our native encephalitides are now endemic. These studies also indicate that species of mosquitoes ( Culex tarsalis, Culex pipiens , See PDF for Structure Aedes dorsalis , and Culiseta inornata ) now known to be fully incriminated vectors of the Western equine or St. Louis encephalitis viruses can also serve as laboratory vectors of the Japanese B virus. Methods for the effective abatement of these species should be further developed and put into practice if future epidemics of encephalitis of the Western equine, St. Louis, or Japanese B types in Western North America are to be prevented or brought under control. Footnotes Submitted: 18 November 1945

Lennette, Edwin H.; Koprowski, Hilary

doi: 10.1084/jem.83.3.195pmid: N/A

The influence of one virus on the growth of another in tissue culture was investigated. The 17DD High strain of yellow fever virus was found capable of completely suppressing the growth of both the Asibi strain of the same virus and of the heterologous West Nile virus, even when these were added to the cultures in large amounts. The 17DD High strain of yellow fever virus and the West Nile virus produced either partial or complete suppression of growth of the Venezuelan equine encephalomyelitis virus, depending upon the quantity of the latter inoculated into the cultures. Owing to lack of methods for the detection of interference except in a single direction, reciprocal interference with these viruses could not be investigated. The 17DD High strain of yellow fever virus and the West Nile virus were able to suppress completely, or almost completely, the growth of influenza A virus added to the infected cultures in maximal amounts. Interference in the reverse direction, even with the use of small amounts of the neurotropic viruses, was not demonstrable. Cultures infected with the 17DD High strain of yellow fever virus were examined for the presence of neutralizing antibodies and non-specific antiviral substances; neither was found present. Footnotes Submitted: 13 November 1945

Boyd, William C.

doi: 10.1084/jem.83.3.221pmid: N/A

Photo-oxidation (in the presence of eosin Y as a sensitizer) of isohemagglutinating sera destroyed their agglutinating activity gradually, but did not seem to convert any of the agglutinins studied into inhibiting ("incomplete" or "blocking") antibody. Footnotes Submitted: 9 December 1945

Kidd, John G.

doi: 10.1084/jem.83.3.227pmid: N/A

Experiments are reported in detail which show that an antibody which appears in the blood of certain rabbits implanted with the Brown-Pearce tumor or injected with cell-free extracts of it is capable of suppressing the growth of the tumor cells under a variety of experimental conditions, the effects of the antibody being wholly distinct from those of unknown factors that frequently bring about regression of the growth. The implications of the findings are discussed with particular reference to facts indicating that the distinctive cell constituent with which the antibody reacts may play a significant part in the proliferative activities of the Brown-Pearce tumor cell. Footnotes Submitted: 28 October 1945

Havens, Walter P.

doi: 10.1084/jem.83.3.251pmid: N/A

1. Serum and stools obtained in the pre-icteric phase of one patient, and pooled specimens of the same materials from 5 patients with experimentally induced (by feeding) infectious hepatitis produced the disease in 10 out of 15 human volunteers following feeding or parenteral inoculation. 2. Pooled specimens of urine and nasopharyngeal washings from 5 patients, obtained in the acute phase of infectious hepatitis when virus was proven to be in the stool and serum, were not demonstrably infectious when fed and given intranasally to 6 volunteers. 3. Serum obtained in the midincubation period of one patient with experimentally induced infectious hepatitis failed to produce apparent infection when inoculated parenterally into 3 human volunteers. This is in contrast to the situation in homologous serum jaundice in which "virus" has been demonstrated in the sera of volunteers during the incubation period. 4. Serum and stools obtained from one patient and pooled specimens of stools from 5 patients 25 to 31 days after onset of experimental infectious hepatitis failed to produce apparent infection in 10 human volunteers. 5. No appreciable difference was detected in length of incubation period following the parenteral administration of widely different amounts of the same strain of "virus." Footnotes Submitted: 20 November 1945